Apparatus for interrupting an electric circuit



May 2, 1939.

F. H. COLE 2,156,450

APPARATUS FOR IN'IZERRUPTING AN ELECTRIC CIRCUIT 3 SheetsSheet 1 Filed June '7, 1937 [/v l/EN TOR FRED h. COLE 5) HARR/s, K/ECH} FOSTER :5: HA RR/J A TTOR VE May 2, 1939. F. H. CQLE 2,156,450

APPARATUS FOR INE'ERRUFTING AN ELECTRIC. CIRCUIT Filed June 7,.193'7 5 Sheets-Sheet *2 56 7 d We 66 65 W V 36 WWI-"MINI" d0 6O FRED H. COLE HA RRAS, K/ECH/ Fos TER @HARR/d 660 A TTORNEV6.

Ma 2, 1939. COLE 2,156,450

APPARATUS FOR INTERRUPTING AN ELECTRIC CIRCUIT Filed June 7, 1937 5 Sheets-Sheet 3 III! n INVENTOR F 250 H. COL

l2? i I q/ M 35 6 AJ'TORNEYJ.

Patented May 2, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR INTER-RUPTING AN ELECTRIC CIRCUIT Fred H. Cole, Glendale, Calif., assignor, by mesne assignments, to General Electric Company, a: corporation of New York I Application June'7, 1937, Serial No. 146,786

18 Claims.

for extinguishing one or more other arcs in the a circuit. In some circuit breakers the gas so generated is applied as a blast directly to the arc' to be extinguished. In the present invention it is contemplated that the blast applied directly to the arc to be extinguished will be substantially completely liquid, and that the gas provided by vaporization of the liquid will have the function of actuating the extinguishing blast of liquid.

If a relatively cool fluid of high dielectric strength is forced through an arc to extract energy therefrom at a greater rate than energy is supplied by the arc, the arc space will become cooler. It has been determined experimentally that if the temperature of the arc space is .1 brought below that necessary to maintain conduction or below the ionization point and the waste products are removed, the arc will be ex-. tinguished and prevented from re-establishin'g.

The general object of the present invention is to employ a blast of a high dielectric liquid for emcient cooling of. an arc and spaces associated therewith, the purpose being to provide such rapid transfer of heat from the arc and removal of waste and ionized products from the vicinity of the arc, that within a desirable time interval the temperature of the arc will drop below the level necessary to sustain the arc.

A further object of my invention is to provide for subjecting successive charges of liquid to the n action of the'generating are, thereby causing the oil blast to be delivered in aseries of high pressure spurts. The .oil blast is characterized by sharp pulsations that account to an important extent for the exceptional results achieved 45' with a given amount of gas generated. It is my purpose to provide such a multiplicity of blast impulses as to favor the occurrence of one or more impulses near or simultaneously with current zero in the arc to be quenched,

50 In my device, I contemplate the employment of a series of blast passages to direct the blast impulses-into various points in the path of the are to be quenched. It is an important object of my invention to provide such communication- 55 between two or more successive passages that the following results will ensue: pressure equalization between the passages preventing escape of oil from the path of advance of the leading end of the generating arc; pressure development in a passage prior to the direct action of-the gener ating arc through that passage; delivery through a passage after the initial blast impulse therethrough of one or more subsequent blast impulses originating in subsequently effective passages.

In the preferred form of my invention, I proe l0 pose to provide successive groups of passages inter-related for pressure equalization as indicated, whereby the series of phenomena resulting from such inter-relation of passages may be repeated during opening operation of the circuit 15 breaker.

In my invention, I employ a hollow arc-quenching member of suitable insulating, and preferably organic, material to provide the voids, such as pockets, slots and passages, required to produce 20 the desired blast effects, and; one of my objects isto achieve those effects by applying certain; principles tothe configuration and disposition of those voids in relation to the arcs involved as will be illustrated by my ensuing disclosure. For 5 example, I have discovered that the minimum cross-sectional dimension of a space into which a loop of an arc maybe forced is approximately one-half inch, and the design of my arc-quench ing member takes into consideration this fact. 30

In the circuit-breaking operation of thepreferred embodiment of my invention, I have the object of causing the arc-quenching member to. move out ofthe fleld'of electrical stress between the contacts that remain connected with the circuit, leaving that field occupied almost entirely by dielectric liquid. By such arrangement, I accomplish the further object of avoiding mechanical members interconnecting said contacts that would. offer paths of reduced electrical resistance 40 therebetween. If the arc-quenching member were to remain between high voltage poles, it would probably flash over after a number of interruptions as a carbon path would build up on this member. A further object here is to cause the arc-quenching member. to move through the dielectric liquid to discourage the accumulation of deposits of relatively lowresistanceon the exterior and interior surfaces of the member. I An advantage of moving the arc-quenching member, instead of the contacts permanently in the circuit, is that the arc-quenching member is relatively light and therefore may be moved with relatively light and simple mechanism. The

diiierence in the cost of construction is substantial, but more important is the fact that the arrangement permits extremely rapid operation of the circuit breaker.

Another'object of my invention is to provide a simple laminated arc-quenching member con= Tstructed of flat plates, thereby avoiding certain problems associated with cylindrical construc tion, including the tendency on the part of cylin= drlcal'walls of oil-blast members to warp out of shape. 1 i

le the principles of my invention may be embodied in oil-blast circuit breakers of various types and ratings, they are particularly appii-= cable to two-break circuit breakers oi apprord= mately 66 kv. rating or lower, and to illustrate these principles, Ishall direct my specific disclosure to such a circuit-breaker.

The 'above and other objects and advantages of my invention will be apparent in my detailed 20 description to follow, taken with the accompany= ing drawings, in which:

Fig. l is a view partly in section or a tanktype circuit breaker incorporating my invention,

{the circuit breaker being in circuit-breaking posiion;

Fig. 2 is a vertical medial section of the arcquenching member with the contacts somewhat separated; v

Fig. 3 is a similar view with the contacts only 80 slightly separated; v

Fig. 4 is a fragment of a similar view showing a pair of contacts in completely closed position;

Fig. 5 is a vertical transverse section on a somewhat reduced scale taken as indicated by the line 5-5 of Fig. 2, one of the contacts being broken away to show the construction of the oilblast member;

Fig. 61s a'similar view taken along the line H of Fig. 2.

Fig. '7 is a slmilarview taken as indicated by the line 'I-I of Fig. 2;

Fig. 8 is a similar view taken along the line 8-4 of Fig. 2;

Figs. 9 to 14 are bottom plan views on a reduced scale of various plates employed to assemble the arc-quenching member;

Fig. 15 is a longitudinal vertical section of a a cross-sectional configuration, the shank being slidably embraced by a complementary guide modified form of my arc quencher;

Figs. 16to 18 are plan views on reduced scale of plates employed in the construction shown in Fig. 15; t

Fig. 19 is a longitudinal vertical section of another modification of my arc quencher;

Fig. 20 is a horizontal section on a somewhat reduced scale taken along the line 20-20,of Fig. 19;'-and i Figs. 21 to 23 are plan views on reduced scale of plates employed in the construction shown in 60 Fig. 19.

that may be employed to practice the invention,

the usual tank, generally designated by the nu-- meral 20, is filled with a suitable oil or other 65 dielectric liquid to a level indicated by the. numeral 2|. The-tank shown is rectangular in configuration, comprising an outer casing 22 and an inner liner 23. The cover 24 of the tank has an inner angular flange 25 adapted to retain a suitable packing member 26 that is normally compressed between the cover and the upper edge of the casing 22. By means such as suitable ears '21 integral with the cover, angle clips 28 mounted on the casing 22, andcoacting bolts 29, the cover may be removably secured to the In Fig. 1 showing one type of circuit breakeraroaeso casing. A "vent (not she) maybe added tothe cover in the customary manner if desired.

A pair oi. insulating'bushings 3t and '30 oi a conventional type is shown mounted on the cover 2d, each bushing extending downward through an aperture 32 in the cover. lin the particular construction indicated, a supporting bushing 33 embraces each of the insulating bushings 3t and 3i and retains a packing sleeve '38 against the periphery of the insulating o. t An overhanging flange 35 at the bottom of each supporting be 33 rests upon a packing ring 36, which ring in turn rests upon a metal ring til around the cover aperture 32. i

The insulating bushings 3t and ti are shown in simplified form to be tubular in construction, enc'asing respectively stationary contacts 33 and 39 in the form of rods oi conducting material extending into the tank below the lower ends of the insulating bushings. Eachof the two contacts 38 and 39, has an annular spacer db and is threaded into a metallic cap 48a at the top of the corresponding insulating bushing, each cap being connected to a wire M of the circuit controlled by my device. v Preferably, thecontacts 38 and 39 are constructed of some arc-resistant material, such as silver-tungsten or copper-tungsten alloys. V

An arc-quenching member generally designated by the numeral 42 of insulating, and preferably organic, material is adapted for movement with respect to the stationary contacts 38 and 39, but

it is to be understood that the operativeness of the arc quencher does not depend upon movement on its part and the principles of my inventtion may well be applied to constructions in which the arc quencher is stationary.

The arc-quenching member 42 is preferably tical bar 46. The bar 46 is mounted as'by screws 4! tea guide shank 48 of square orxrectangular sleeve 49 mounted in the tank cover 24. By virtue of this construction, the arc-quenching member 42 is guided along a. vertical linear path and prevented from rotation during its movement.

In" the simplified construction shown,'vertical movements of the arc quencher 42 are controlled by a rocker arm 50, the rocker arm having a. suitable slot 5| in engagement with a pin 52 associated with the guide shank 48. A shaft 53, to which the rocker arm is keyed, extends thropgh the wall of the casing 22, being suitably journalled therein, and carries on the exterior of the tank a second rocker arm 54. This second rocker arm is .operatively connected to an actuating mecha- 1 nism (not shown) through the medium of a suitable connecting rod 55. v

Preferably, I provide a plate 23a on the interior of the tank liner 23, opposite the path of move- I contemplate providing in vertical sequence a series of horizontally disposed voids, each void including a gas-generating chamber 56 and a blast passage generally designated by the numeral 51 leading from that chamber to anarc-space 58. The purpose of each chamber 56 is to cooperate with one of the arcs formed in the opening operation of the circuit breaker to generate gas by vaporization of the entrapped oil, and the purpose of each blast passage is to direct the stream of liquid oil driven by the gas into a second are formed in the arc-space 58.

In the preferred form of my invention shown, a somewhat narrow pocket 59 is formed in the side wall of the generating chamber 56 opposite from the passage 51 and is disposed in the direction of the tendency of the generating arc to loop Outward from the second arc. Preferably, the blast passage is not of uniform cross-section, but comprises, first, a relatively wide passage 60 leading 'vide the required series of voids including generating chambers and blast passages. A feature of my invention in the preferred form is the employment of a laminated construction for the arc-quenching member 42, the member being assembled from a plurality of plates variously shaped as indicated, for example, by Figs. 9 to 14 inclusive. While my invention will operate with complete satisfaction if the plates are made of such non-absorbent, inorganic materials as glass and porcelain, I prefer to employ some organic fibrous material well known for such use.

The uppermost plate in the assemblage as shown in bottom plan in Fig. 9, has two beveled apertures 66 and 61 to receive respectively stationary contact rods 38 and 39. For the purpose of unifying the assemblage, a plurality of downwardly projecting pins 68 of insulating material may be mounted on the bottom of the plate 65 to project downward through complementary openings 68a, in'the remaining plates, the pins being provided with suitable nuts 69 at the bottom of the assemblage. Beneath this uppermost plate 65, relatively thin plates forming walls or partitions alternate with relatively thick plates that are shaped to provide the required series of generating chambers and blast passages. Thus, in the drawings thin plates 10, 10a,'10b, 18c, 10d and 10a alternate with thick plates Ila, 1lb, 1lc, 1| d,

.1le, and 1|), each thin plate providing a horitoward the wall opposite from the blast passage 51, so that the forces generated in the chamber tend to be directed toward such passage, and so that the generating arc itself offers minimum interference with the escape of gas from the generating chamber. It may be noted that when the contact rod 38 extends downward through the arc-quenching member 42, it fits into opengroups of inter-related passages.

lugs 12 with .sufllcient closeness to effectively isolate the generating chambers from each other, and that as the arc-quenching,member is withdrawn from the contact 38, the openings 12 and the generating chambers 56 are successively uncovered to form a continuous space for the generating arc.

Each of the thin plates 10 also has a second contact-receiving opening 13 complementary to the second contact rod 39. It is contemplated here that when the circuit breaker is closed, the contact 39 will fit with sufficiently close clearance into the openings 13 to effectively seal or blast passages 51 from each other, and that in the opening operation of the circuit breaker, the arc-spaces 58 and the holes 13 will be uncovered successively to form a continuous space for the arc associated with the contact 39. Itis further contemplated that the dimensions of the arcspaces 58 with respect to the diameter of the contact 39 will be such that within the extremely.

short time intervals of operating time, the contact will in effect close off the blast passages 51 in the manner of a valve. Since the passages 51, together with the generating chambers 56, constitute in effect blind passages, it is apparent that fluids therein are trapped until released by withdrawal of the contacts 38 and 39.

Thin plates 10, 18b, and 10d have very narrow and relatively short slots .16 extending outward from the contact-receiving openings 13, as shown in plan in Fig. 11, and the alternate thin plates 10a, 1110, and 10e have similar but longer slots 15, as shown in plan in Fig. 12.

A feature of my invention, as heretofore mentioned, is the inter-relation of voids of adjacent levels to provide for the transmission of pressure from one level to another. By preference, such provision for pressure equalization will be made only between certain levels so that the plurality of levels as a whole will be divided into In this manner I provide for repeating, during the opening operation of the circuit breaker, whatever useful phenomena are incidental to pressure equalization between adjacent levels. In the preferred form of my invention set forth in the drawings,

I inter-relate the levels by pairs and provide 7 three of such inter-related groups. Thus, the plates 10b and 10d, being of the configuration shown in Fig. 11, provide continuous partitions between the contact-receiving openings 12 and 13 to isolate the generating chambers and blast passages on either side of those plates to an effective extent; but, the plates 10a, 1110, and 10e that separate levels within, agroup are provided with equalizing openings 11, as shown in plan in Fig. 12. Preferably in each of theseplates there is a relatively narrow slot 18 extending from the pressure-equalizing opening 11 to the contactreceiving opening 12, and a second relatively narrow slot 19 extending a short distance from the pressure-equalizing opening toward the other end of the plate, as indicated in Fig. 12. Immediately below the plate 1|f is a relatively thick plate 80, as shown in plan in Fig. 13,

the plate having apertures 8| and 82 to receive respectively lower contacts 83 and 84- that are complementary to the upper stationary contacts 38 and 39. The plate has a short, narrow slot 14a, corresponding to slots 14 of the plates 10, 10b and 16d. Immediately below the plate 80 is a thinner plate 85 (Fig. 14) having relatively large openings 86 registering with the openings of the plate 80 and having ears 8lla-to receive 5 tegral flange 88 that seats against the correv sponding bushing 31 when the contact itself extends to the level represented by the upper face of the plate 80, as shown in Figs. 2 and 3; Each of the two contacts 83 and 84 has a guide stem 89 1 that extends'downward into sliding engagement with a guide aperture 90 in a closed contact housing 9| mounted on the bottom of the arcquenching member 42 (Fig. l).- A suitable spring 92 noting between the housing 9i and the 5 flange 88 serves to urge the contact continuously upward, and a shoulder 93 on the contact stem 89 is dimensioned to engage the housing St tolimit the downward movement of the contact. The. two contacts are interconnected by a conducting 20 member 94 to close the circuit between the two pairs of contacts. j

When the circuit breaker is in its normal, 1. e., closed circuit position, the stationary contacts depress the corresponding lower contacts as indi- 25 cated in Fig. 4. By virtue of this yielding arrangement for the lower contacts, proper engagement between the contacts is insured and the shock of closing the contacts is cushioned. The fact that the contact housing 90 constitutes a closed receptacle prevents the escape of fluids downward past the lower contacts 83 and 84.

If a relatively low current are is submerged in a. dielectric fluid, the gas generated by vaporization of the fluid forms a large bubble that iso- Iates the arc from the liquid and tends to reduce the rate of gas generation, in which case the -amount of gas generated may be too low to provide sufflcient energy to extinguish an are. On I the other hand, a submerged arc energized by 4,0 relatively high current tends to wander energetically about the surrounding liquid with the result that the quantity of gas generated is vastly in excess of the energy required to extinguish the arc. For satisfactory circuit interruption through 45 a range of currents, it is required, therefore, that the arc-quenching structure provide a relatively large amount of blast energy per ampere for small currents, but a substantially smaller ratio for large currents. An arc quencherdesigned solely 56 with considerations for the requirements of interrupting large currents probably would not develop sufiicient energy to extinguish a low current arc; and an arc quencher designed solely to meet the requirements of low current operation 55 would probably developa disastrous amount of gas pressure when extingui a high current are. Since it is my object to break the circuit towards the end of a half cycle near a current zero when the energy of the circuit is most apt to be m at a minimum, the problem of large current operation is to avoid such violent blast action as would break the current in the middle of a half cycle when the energy of the circuit may be disastrously 5 h h A feature of an arc quencher constructed in. accordance with my design is that while it favors generation of a relatively large quantity of gas with a low current are by preventing the forma- 70. tion of large bubbles, by insuring in a positive manner intimate association of the arc with the liquid, by trapping the liquid to be gasified, and by providing for subjecting successive charges of liquid to the arc} it also controls the gas-gener- 75- ating activities of high current arcs by co areas-to the range of the generating are are relatively extensive. It will be noted that the narrowness of oil to the desired extent.

.the lowermost throttle passage 82, and when the such arcs to a limited zone of action and by limiting the quantity of oil exposed to the arc.

When the contacts first begin to separate, as indicated by the positions of the contacts shown in Fig. 2, the oil in the lowermost level of voids is 5 immediately acted upon by the generating arc. Even when the contact 39 is raised, as shown in Fig. 2,,c1ear of the lowermost level of voids the formation of the generating arc is so rapid, the inertia of the oil body so great relatively, and the lowermost throttle passaget! has such a retarding action, that the oil cannot escape ,the arc in the extremely short time interval involved in breaking a circuit. I

Rapidity of gas generation is enhanced by the fact that the generating arc ismagneticallymoved outward into the lowermost oil pocket 59 and by the fact that the arc and the surrounding liquid are confined to spaces of restricted cross-sectional dimensions.

A further factor in determining the rate of gas generation is that the surfaces of oil-soaked,

organic material bounding the generating chambers 56 and bounding the blast passages 5'! within be pointed out. When the contacts are in the positions indicated by Fig. 3, the pressure from below exerted upward around the contact 38 tends to move the oil body in the next level away from that contact. This tendency is neutralized, however, by the fact that pressure from the lowermost level is also transmitted through the lowermost pressure-equalizing opening TI to the second level, so that pressure on the oil in the second level immediately around the contact 38 is effectively equalized. Further factors favoring'continuous blast forces are that each blast passage provides an adequate 50 volume of oil for sustained flow against the arc .to be extinguished. The fact that each blast passage is throttled or restricted at 62 is of importance here as prolonging the release of this An important function of the equalizing openings ll should be noted, When the contact 38 rises to the uppermost level of a group of levels, the blast forces generated in that uppermost level Will'be transmitted through the associated presg0 sure-equalizing means to lowerlevels of the group contacts are in the positions shown in Fig. 3, an

initial impulse originating in the lowermost generating chamber will be directed outward through contacts separate to theextent shown in Fig. 2,

a subsequent impulse through the lower throttle passage 62 will be transmitted from the generating chamber of the second levelthrough the lowermost pressure-equalizing opening 11. Also. 7

noted here as contributing to this phenomenon is the fact that the throttle 62 of the lowermost level serves to maintain pressure in the lowermost level, the result being that the full effect of the blast impulse from the upper level is felt immediately at the discharge end of the passage.

With respect to efficiency in the utilization of a given amount of blast energy without consideration of the efllciency with which that blast energy is generated, it may be pointed out that I increase the effectiveness of the blast energies available by transmitting thoseenergies as a succession of explosive impulses directed into the body of the arc to be extinguished. The multiplicity of these impulses is accounted for by the fact that successive fresh bodies of oil are subjected to the action of the generating arc, and the fact that where there is a pressure-equalizing means immediately below the impulse force originating in a given level, that impulse force is exerted simultaneously on a plurality of levels.

Slots 18 and 19 associated with the equalizing openings may enter into various phases of the operations described, by serving to retain oil for blast-generation and by ofi'ering additional surfaces of gas-evolving material.

I have found thata loop of an are subject to the force of an oil blast cannot be driven into a passage of substantially less than one-half inch in cross-sectional dimension. For example, a passage no larger than three-eighths of an inch in cross-section would be inoperative. If the spaces provided for displacement of the arc to be extinguished are substantially less, they serve no purpose; on the other hand, to provide spaces of much greater cross-sectional dimension is to make the arc-quenching member of unnecessarily large size. For efficiency of operation as well as economy of material, I prefer to make the relatively thick plates Ila, llb, Hc, 'Hd, He, and III approximately one-fourth inch in thickness and the thin plates 10, 19a, 10b, 10c, 10d, and m approximately one-eighth inch in thickness; It will be apparent, then, that two adjacent levels in the arc quencher provide a space of sufilcient cross-sectional dimension to permit displacement of the are by the forces of the oil blast, a narrow slot such as a slot 14 or a slot I not interfering with such displacement.

When the contacts of the circuit breaker initially separate to the extent indicated by Fig.

3, gases generated in the lowermost generatingr the associated blast passage between the two pairs of contacts, and the oil in the blast passage is moved towards the are between the contacts 39 and 84 and, in effect, acts as a liquid piston driven by the generated gas. Since the contacts 39 and 84 are slightly separated at the instant under consideration, the force of the oil blast from the lowermost level is exerted not only through the exhaust passage 63 of that level, but also upward through the narrow slots above that passage. As a result of such forces; as well as of the magnetic forces involved, the arc to be extinguished will probably bow outward as indicated by the dotted line 95 of Fig. 3.

When the opening movement of the circuit breaker progresses to the point indicated by Fig. 2, extending the are into the generating chamber of the second level, the new charge of oil in the second generating chamber and the associated pocket 59 will be vaporized in an explosive manner and cause a powerful spurt of oil in the second level of the arc quencher. By virtue of the equalizing opening I1 between these two levels the same forces will also be exerted against the liquid piston in the lower level so that jets of oil will be discharged into the arc space 58 at two levels simultaneously.

At this point in the opening movement of the circuit breaker the arc ,to be extinguished may be displaced into an irregular loop asindicated by the dotted line 96 in Fig. 2; Under the forces of the oil blasts of the two levels the arc has been extended in length at a considerably faster rate than the rate of opening movement of the circuit breaker.

It will be noted thateach pair of exhaust passages 63, having in common a slot 15, constitutes a space for the displacement of the arc, since the two passages measured through the slot are more than one-half inch in cross-sectional dimension; but beyond the slot the end portion 91 of the intervening plate (Fig. 12) serves as a barrier to limit the displacement of the arc. The electric arc tends to avoid the oil blast but, being confined to thesame channels as the oil blast, cannot escape the effects of the blast. In this connection it will be apparentthat barriers 91 not only tend to confine the arc to the exhaust passages but also serve to retard the escape of oil from the interior of.the arc quencher. In the meantime, the -are having beendisplaced to the new path indicated in Fig. 2, the cooling action of fresh oil is effective on the original path and immediately completely de-ionizes the zones initially occupied by the arc. It will be apparent that fresh cool oil is continuously moved into the arc to deprive it of heat and ions.

In the performance of the circuit breaker described, an arc of as high as 15 kv. will always be extinguished before the second level of the arc-quenching member is reached, and an arc of as high as 66 kv., the full rating of the circuit breaker, will not exist past the third and fourth levels ofthe arc quencher. I

The modification of my arc quencher shown in Fig. 15, the circuit breaker being partly open, is

similar in general to my preferred are quencher previously described, corresponding numerals being employed to indicate corresponding parts. The important features of this modification are the employment of relatively narrow contacts and the provision of equalization through all the levels of the arc quencher.

Upper contacts 38a and 39a, as well as lower contacts 83:]. and 84a, are relatively narrow in cross-sectional configuration with their long dimensions extending transversely of the arc quencher. The lower contacts 83a and 8411 are yieldingly mounted on the arc quencher in the manner previously described and are interconnected by a conductor 94a. e

The arTc quencher is constructed preferably by to conform with the cross-sectional configurations of the two lower contacts 83a and 84a.

Between the'top plate a and the lower plate 80a, thin plates alternate with thick plates to provide passages at successive levels and to provide an equalizing chamber generally designated by the numeral 98 that is common to all of these levels. I prefer to provide this equalizing chamher with a transverse barrier generally designated by the neral 871, the barrier extending downv ward from the top of the chamberto a point spaced from the bottom thereol.

Thin plates 88 have the cated in Fig. l7, each plate having a contactreceiving opening 99 for the contact the, a pair til of equalizing openings MB separated by a transverse wall Hill to constitute a part ofthe barrier $7, a contact-receiving opening m2 for the contact 139a, and a slot tilt extending from the opening Hi2 longitudinally of the plate. Thin plates tilt have the configuration indicated by Fig. 18. The plates w l are similar to plates in having contact-receiving openings 99 and W2 and in having the equalizing openings ilili separated by the wall itl they difier, however, in

having longitudinal slots M35 extending from the opening 99 to the first equalizing opening Mill and differ in having slots lot substantially longer than the corresponding'slots ills of the plates 98.

Thick plates Hill of the levels through which the barrier 91 extends have the configuration indicated by Fig. 16', each plate providing an oil pocket llll, a blast-generating chamber ill, a passage H2 having'an expanded portion lit, a transverse wall Ill across the expanded portion of the passage to constitute a portion of the barrier 91, a restricted passage ill, a contactreceiving opening H8, and an exhaust passage H9.

A thin plate l2. has the same configuration as the'plates l 04 previously described, but the transverse wall IN is omitted with the result that the plate has a. single equalizing opening tilt instead of two. Since the pressure equalization provided'by the chamber 95 extends through all the levels of the arc quencher, the arc quencher may be considered as comprising a single group of interconnected passages as distinguished from the plurality of groups of passages in the arc quencher first described.

As the generating arc is extended upward in the arc quencher shown in Fig. 15, the barrier 9'5 prevents generated -"gas from moving directly across the upper levels of the arc quencher. The

barrier 91 deflects the gas into a circuitous path,

or it may be said that gas generated at the upper levels is trapped in theportion oi the equalizing duce the length of fluid flow necessary to fill this wideninggapand thereby reduce the time re-' ,quired for cooling that gap.

The purpose of including in my disclosure the modification shown in Fig. 19 is to illustrate, by

- way of example, how the arc quencher of Fig; may be modified by omitting the transversebarrier in the equalizing chamber and/or by turn-' ing' the relatively-narrow contacts into longitudinal alignment with the arc quencher. The construction shownin Figs.'19 and 20 is similar tov the construction previously described, corresponding numerals being employed todesighate corresponding parts. In Fig. 19 upper con- I claim as my invention:

aisacso tacts 88b and 3% are stationary while'lower contacts @312 and Mb are yieldlngly mounted in the are quencher, the two contacts being interconnected by a bonductor 9%.

As in the previously described constructions, the arc quencher is constructed preferably by assembling a number of flat plates, the assembly being held together by nuts till) engaging pins tilt) and being connected to actuating mechanism by means such as previously described, including a pair of bolts A31). The top plate 65b of the assembly is provided with tapered apertures (5th and till) to receive respectively the stationary contacts 3% and 3912. At the bottom of the arc quencher is a thick plate Filth and a thin plate 81% suitably apertured to conform with the crosssectional configurations of the twd lower contacts iillb and 84b.

Between the top plates hill) and the lower plates lillb, thin plates alternate with thick plates to I provide passages at successive levels and to procontact-receiving opening H6 and equalizingopening i25, but differs in having a slot l28 ex-' tending from the first contact-receiving opening to the equalizing opening and in having a second slot I29 extending longitudinally from the second contact-receiving opening.

Thick plates I30 have the configuration indicated by Fig. 22, each plate providing an oil pocket i3l, a blast-generating chamber in, a passage !33 having an expanded portion I34, and a restricted passage I35 that is continued as an exhaust passage I36.

This form of the invention operates in the:

same manner as the/form shown in Fig. 15 with the exceptions involved in omitting the transverse barrier in the equalizing chamber and in turning the contacts into longitudinal alignment. The

fact that 'the contacts 3%. and 84b are aligned with the slots I29 is believed to be an advantage..

since the slots are conveniently accessible to the arc.

Changes providing other. forms and modifications of .my invention within the scopeof my conception are suggested by the specific examples jherein set forth; I reserve the right to all such variations that properlycome within the purview of my appended claims.

1. A circuitv breaker having in combination: an

arc-quenching memberof insulating material coni taining a dielectric liquid; means forforming a plurality of arcs in said arc-quenching member in the circuit to be interrupted; a plurality of passages in mean-quenching member leading from the-path of one or said arcs to the path of another of said arcs whereby pressure of gas generated by the first arc will cause blasts of liquid to .be'clirected across the path of the second arc; and pressure-equalizing openings intermediate the two arcs interconnecting at least some of said passages. v

2 A circuit breaker having in combination: means to form two arcs in a circuit; an. arcquenching member of insulating material containing' a dielectric liquid; a plurality of blind ner ends in the vicinity of the path of one of said arcs and directed outward across the path of the other are; and pressure equalizingopenings interconnecting said passages.

ber in the circuit to be interrupted; a plurality of passages in the arc-quenching member leading from the path of one of said arcs to the pathof another of said arcs whereby pressure of gas generated by the first arc will cause blasts of liquid to be directed across the path of the second arc, said passages being divided into separate groups of passages; and pressure-equalizing means interconnecting the passages of each of said'groups.

4. A circuit breaker having in combination: an arc-quenching member of insulating material containing a dielectric liquid; means for forming a plurality of arcs in said arc-quenching member in the circuit to be interrupted; a plurality of passages in the arc-quenching member leading from the path of one of said arcs to the path of another of said arcs whereby forces generated by the first arc drive blasts of liquid across the path of the second arc, said passages being divided into separate groups of passages and said passages being throttled at their discharge ends;

"and pressure-equalizing means interconnecting quenching member of insulating material contaming dielectric liquid; a plurality of blind passages in said member terminating at their inner ends in the vicinity of the path of one of said arcs and directed outward across the path of the other arc; pockets at the inner ends of said passages disposed in the path of the looping tendency of the corresponding arc; and pressureequalizing openings interconnecting at least some of said passages.

6. A circuit breaker having in combination: means to form two arcs having tendencies to loop outward away from each other; an arc-quenching member of insulating material containing dielectric liquid; a plurality of blind passages in said member terminatingat their inner ends in the vicinity of the path of one of said arcs and directed outward across the path of the second arc; pressure-equalizing openings interconnecting some of said passages; a pluralityof spaced barriers in the arc-quenching member disposed on the looping side of the second arc; and narrow slotsin said barriers disposed in the path of the looping tendency of the second arc and terminating-short of the end of the arc-quenching mem ber.

7. A circuit breaker having in combination: an arc-quenching member immersed in a dielectric liquid; a plurality of gas-generating chambers in said member; contact-receivingopenings interconnecting said chambers; contact means operative through said openings with sufficiently close fit to substantially seal off said chambers from each other when the circuit breaker is closed,

last openings with sufficiently close fit to substantially seal ofl said passages from each other in the closed position of the circuit breaker, said means being adapted to draw an arc across said passages, each of said passages being dimensioned so as to be substantially closed by said second contact means; and pressure-equalizing means interconnecting at'least some of said passages intermediate the two contact means whereby pressure generated by the arc in the chamber assoextinguish the first arc; arc-receiving pockets in the wall of said chambers opposite from said passages; and arc-receiving slots in the walls separating said passages.

9. A circuit breaker having in combination: an arc-quenching member containing dielectric liquid; a plurality of gas-generating chambers in said member; a plurality of blast passages from said chambers to the exterior of said member; means to draw an arc across said passages; means to draw an are through said chambers offset from the centers of said chambers to be adjacent the walls thereof opposite from said passages whereby forces will be directed toward said passages to propel liquid therethrough to extinguish the first arc; and pressure-equalizing openings interconnecting some of said passages.

10. A circuitbreaker having in combination: a stationary set of contacts submerged in a dielectric liquid; a movable set of contacts also submerged in the dielectric liquid and forming pairs of contacts with said stationary set; a movable arc-quenching member in said liquid normally encompassing said contacts in their closed positions; a plurality of pockets in said member in the vicinity of one of said pairs of contacts to provide liquid for generation of gas. by an arc across said pair of contacts in the opening movement of the circuit breaker; said pockets being progressively uncovered in accordance with said opening movement; a plurality of passages in said member leading from said pockets respectively past a second pair of said contacts to provide liquid for liquid blasts driven by said generated gas; and means to move both said arc-quenching member and said second set of contacts to provide the opening and closing movements of the circuit breaker, said means moving the arcquenching member entirely clear of the stationary contacts.

11. A circuit breaker having in combination: a, receptacle containing a dielectric liquid; an arcquenching member movably mounted for movement in said liquid; a plurality of pockets in said member entrapping liquid for progressive generation of gas by the action of agenerating arc; a

plurality of passages individually communicating with said pockets respectively containing liquid for the extinction of a second arc; a pair of contacts comprising a contact fixedly mounted in the receptacle and a contact mounted on the arc quenching member, said contacts being disposed to form a generating arc in said pockets successively; a second pair of contacts including a stationary contact mounted in the receptacle and a contact mounted on the arc-quenching member, said contacts being disposed to draw an arc to be extinguished across said passages successively; and means to move said arc-quenching member towards and away from said stationary contacts.

12. A circuit breaker having in combination: a receptacle containing a dielectric liquid; an arc-quenching member movablymounted in said liquid; a plurality of voids in the arc-quenching member for the generation and direction of arcextinguishing blasts, said voids opening to the exterior of the arc-quenching member; contactreceiving openings communicating with said voids disposed to accommodate an arc to generate gas for blast energy and, an arc to be extinguished by said blasts; pressure-equalizing openings interconnecting some of said voids; contacts in said openings carried by the arc-quenching member;

corresponding contacts permanently connectedwith the circuit to be interrupted and fixedly mounted in the receptacle in alignment with said openings; and means to move the arc-quenching member towards and away from said fixed contacts to open and close said circuit.

13. A circuit breaker having in combination: an arc-quenching nieans of insulating material immersed in a dielectric liquid; contact means to draw a generating arc in said arc-quenching member; contact means to draw an arc to be ex tinguished in'said arc-quenching member; an

equalizing chamber in said arc quencher intermediate said contact means; a plurality of passages leading from said first contact means to the euqalizing chamber;and a plurality of passages leading from said equalizing chamber past said second contact means.

14. A circuit breaker having in combination: an arc-quenching means of insulating material immersed in a dielectric liquid; contact means to draw a generating arc in said arc-quenching member; contact means to draw an arc to be extinguished in said arc-quenching member; 'an equalizing chamber in said are quencher intermediate said contact means; a plurality of passages leading from said first contact means to the equalizing chamber; a plurality oi? passages leading from said equalizing chamber to said second contact means; and a gas-deflecting barrier in j the equalizing chamber.

' 15. A circuit breaker having in combination: an elongated passage having a cross-sectional dimension of not substantially less than one-half inch at its entrance and having maximum crosssectional dimensions substantially under one-half inch at its exit; means to draw an arc across the entrance of. said passage; and means to direct a blast of fluid into said passage in a manner to force a loop of the are into the passage. 7

164 A circuit breaker having in combination:

means to generate an arc to be extinguished;

means providing a passage having anentranceadjacent said arc, the entrance of said passage and a substantial portion thereof near the entrance being not substantially less than one-half inch in cross-sectional dimension to accommodate a loop of said are, said passage being restricted to substantially less than one-half inch in cross-sectional dimension towards theexit thereof to prevent extension of said are loop beyond said exit;

and means providing a fluid blast to drive said loop of the are into said passage.

17. A circuit breaker of the fluid blast type .comprising means forming an interruptingarc within an arc-extinguishing fluid upon opening of '1 the circuit, an insulating exhaust passage extending transversely from the path of said are and having an entrance portion into said are which can be looped by a blast of said fluid said passage having a portion restricted as compared with said entrance portion toward the exhaust part of said passage for limiting the extent of looping of said arc, and means for creating said fluid blast for driving said are into said passage.

18. A circuit breaker oi the oil blast type com- 

